System for installing tubing encapsulated cable into coil tubing

ABSTRACT

Tubing encapsulated cable is generally difficult to place in the interior of coil tubing while the coil tubing is wound onto a reel on the surface. In various embodiments of the present invention tubing encapsulated cable is placed in the interior of coil tubing by first installing a semi-rigid cable into the coil tubing semi-rigid cable is initially installed by pumping the cable into the coil tubing. The leading end of the cable is then attached to a winch while the trailing end of the cable is attached to tubing encapsulated cable. The winch applies tension to the cable in turn pulling on the tubing encapsulated cable to move the tubing encapsulated cable into the coil tubing. Additionally fluid is pumped through the tubing encapsulated cable in the direction that the tubing encapsulated cable is being installed to assist in overcoming the capstan effect that acts on both the cable and the tubing encapsulated cable. Also the coil tubing may be vibrated to assist in overcoming the capstan effect while installing the tubing encapsulated cable into the interior of coil tubing while the coil tubing is on a reel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 61/915,231 that was filed on Dec. 12, 2013.

BACKGROUND

Tubing encapsulated cable can be difficult to insert into coil tubing. Tubing encapsulated cable typically consists of one or more electrical conductors, a fiber optic cable, and possibly other cables or lines sheathed in a corrosion resistant alloy such as 316 stainless steel or a fiber reinforced composite sheath. The smooth outside surface and relatively small diameter of tubing encapsulated cable are desirable attributes for well intervention work because the relatively smooth surface may be more resistant to chemical attack than braided wire. Additionally, the relatively smooth surface and small diameter (0.125″-0.250″) minimizes viscous drag exerted upon the cable as fluids pumped through the coil tubing in the course of intervention operations pass by the cable. Because there is little drag on the tube wire, conventional pumping operations used to install braided wireline into coil tubing are not sufficient to install tubing encapsulated cable. Pumping fluid through the coil tubing during the installation of tubing encapsulated cable is required to assist in overcoming the capstan effect, caused by the friction between the coil tubing and the tubing encapsulated cable as the tubing encapsulated cable travels through the wound coil tubing.

There are numerous techniques that may be utilized to install tubing encapsulated cable into a long tubular member such as coil tubing. Such as hanging the coil into the well in order to allow the somewhat reliable force of gravity to pull the tubing encapsulated cable downward into the interior of the coil tubing. Another commonly known technique involves spooling out the coil tubing along a roadway, installing a rope, cable, or equivalent and using the rope or cable in a manner similar to that of an electrician's fish tape to pull the tubing encapsulated cable into the coil tubing. In these instances fluid may or may not be pumped into the coil tubing inserting the tubing encapsulated cable. Inserting the tubing encapsulated cable into coil tubing as described above can be an expensive operation. Wire and cable have been used with a tubular conduit since the late 1800s, conduit, like coil tubing, is a long tubular member that normally has wires and cables with a wide variety of outer armors run through it.

SUMMARY

One solution to the problem of running a long tubing encapsulated cable into coil tubing is to insert a long semi rigid element into the coil tubing while the coil tubing is wrapped on a reel. Typically, the long semi rigid element that is longer than the coil tubing that the long semi rigid element is inserted into. A first end of the semi rigid member is inserted into a first end of the coil tubing with the tubing encapsulated cable attached to an end, typically the second or trailing end, of the semi rigid member. The semi rigid member is inserted into the first end of the coil tubing to the point where first end of the semi rigid member may be accessed from a second end of the coil tubing. The long semi rigid member is then retrieved from the second end of the coil tubing. As the semi rigid member is retrieved from the second end of the coil tubing, the tubing encapsulated cable is pulled through the coil tubing. Upon the second end of the semi rigid member reaching the second end of the coil tubing the tubing encapsulated cable is disconnected from the semi rigid member leaving the tubing encapsulated cable inserted along the length of the interior of the coil tubing. In certain instances it may be necessary to pump fluid through the coil tubing as the semi rigid member is inserted or retracted to break the capstan effect.

It may be desirable to have the semi rigid member wrapped on a reel with a similar diameter to the coil tubing reel holding the coil tubing that the semi rigid member is inserted into. To avoid the capstan effect, it may be desirable for the semi rigid member to be curved with a similar curvature to the coil tubing that the semi rigid member is being inserted into to reduce friction between the semi rigid member and the coil tubing. Reducing such friction tends to reduce the forces necessary to insert the semi rigid member into the coil tubing and increase the likelihood of a successful insertion operation. In this scenario, care should be taken to avoid plastic bending of the semi rigid member into a straight condition or other configuration that does not match the profile of the coil tubing as the semi rigid member is inserted into the coil tubing.

Fish tapes are commonly used by electricians in the construction industry to pull wire into conduit. Typically the conduit consists of long, straight runs of a few hundred feet with an occasional bend in the conduit to go around corners. These fish tapes are typically made from a thin strip of carbon steel with an eyelet on the end to facilitate attaching the wire to the fish tape. It is not uncommon for the coil tubing used in the energy industry to be orders of magnitude longer than a typical conduit run where conventional fish tape is used to pull in wiring. Additionally, it is desirable to install the tubing encapsulated cable into the coil tubing while the coil tubing is wrapped around a reel; hence there are no straight runs. The constant curvature tends to create a capstan effect and lock up a cable or similar elements that are pulled through it.

It is common practice to pump a cable into coil tubing while it is laid out straight and then use the cable to pull in a smaller diameter cable such as tubing encapsulated cable. The method described in this disclosure differs from the other solutions because the coil tubing may be wrapped around a reel while the tubing encapsulated cable is being pulled into the coil tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a spool of coil tubing mounted on a reel.

FIG. 2 depicts a semi-rigid or other cable as it is fed from a spool into the coil tubing.

FIG. 3 depicts a cable as it is pulling the tubing encapsulated cable from spool into whip end of coil tubing.

FIG. 4 depicts the coil tubing on reel after the installation of the tubing encapsulated cable through the length of the coil tubing.

DETAILED DESCRIPTION

The description that follows includes exemplary apparatus, methods, techniques, or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

FIGS. 1-4 depict an embodiment of a process for installing a tubing encapsulated cable into a spool of coil tubing.

FIG. 1 depicts a spool of coil tubing 10 mounted on a reel 12. The reel 12 is typically used to store and transport the coil tubing 10. When the coil tubing 10 is wound onto the reel 12 the process begins by inserting a leading portion of the coil tubing 10 referred to as the core end 14 into the interior 16 of reel 12. Once the reel 12 is filled the trailing end of the coil tubing 10 referred to as the whip end 18 is accessible from the exterior of the coil tubing 10.

FIG. 2 depicts a semi-rigid or other cable 20 as it is fed from a spool 22 into inlet 26 of flow tee 24. Outlet 30 of flow tee 24 is connected to the whip end 18 of coil tubing 10. Water or other fluid is pumped into inlet 28 of flow tee 24. The water then flows out of flow tee 24 into whip end 18 of coil tubing 10 and then through the coil tubing 10 to the core end 14 where it exits the coil tubing 10. As the water flows through coil tubing 10 it exerts drag on the cable 20 there by pulling the cable 20 into and through the coil tubing 10, eventually causing at least the leading end of the cable 20 to exit from core end 14 of coil tubing 10 while the trailing end of cable 20 has not yet entered flow tee 24. In some instances a plug or other high drag fitting may be placed into the interior of the coil tubing 10 and attached to cable 20 in order to help pull cable 20 through the length of coil tubing 10.

FIG. 3 depicts the cable 20 as it is pulling the tubing encapsulated cable 40 from spool 42 into whip end 18 of coil tubing 10. A cable winch 44 is attached to the leading end of cable 20 extending from core end 14 of coil tubing 10 the cable 20. The trailing end of cable 20 is attached to tubing encapsulated cable 40. The cable winch 44 begins to apply tension to cable 20 in order to draw cable 20 and in turn tubing encapsulated cable 40 through flow tee inlet 26, through the flow tee 24, and through the spooled coil tubing 10 mounted on reel 12. As tension is applied by cable winch 44 to cable 20 and tubing encapsulated cable 40 the loops of cable 20 and tubing encapsulated cable 40 tends to tighten on the radially inward surfaces of the coil tubing 10 is spooled onto reel 12. In order to overcome this capstan effect is been found beneficial to pump fluid into inlet 28 of flow tee 24 and thereby through the coil tubing 10 while applying tension to cable 20 and tubing encapsulated cable 40. As the fluid passes by cable 20 and tubing encapsulated cable 40 it tends to interact with the cable 20 and tubing encapsulated cable 40 to pull both in the direction of the fluid flow. The drag on cable 20 and tubing encapsulated cable 40 by the fluid tends to help overcome the capstan effect thereby allowing the winch to continue to pull the cable 20 and tubing encapsulated cable 40 through the length of the coil tubing 10 as it sits on reel 12. In some instances it is also been found helpful to vibrate the coil tubing 10 in order to help overcome the capstan effect between the interior of coil tubing 10 and cable 20 and tubing encapsulated cable 40. Fluid pumping and vibration may be used together or independently to overcome the capstan effect.

FIG. 4 depicts the coil tubing 10 on reel 12 after the installation of the tubing encapsulated cable 40 through the length of the coil tubing 10. Some length of tubing encapsulated cable 40 extends from both the whip end 18 of coil tubing 10 and the core end 14 of coil tubing 10.

While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.

Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter. 

What is claimed is:
 1. A method of installing a tubing encapsulated cable comprising: inserting a cable into a first end of a coil tubing, wherein the coil tubing is wound on a reel, pumping fluid into the first end of the coil tubing, moving a first end of the cable through the coil tubing, connecting a second end of the cable to a tubing encapsulated cable, applying tension to the cable, and pulling and pumping the tubing encapsulated cable through the coil tubing.
 2. The method of claim 1 wherein, the first end of the coil tubing has a flow tee.
 3. The method of claim 1 further comprising, connecting the first end of the cable to a winch after the first end of the cable moves through the coil tubing.
 4. The method of claim 1 further comprising, connecting the first end of the cable to a plug prior to moving the first end of the cable through the coil tubing.
 5. The method of claim 1 further comprising, vibrating the coil tubing while pulling and pumping the tubing encapsulated cable through the coil tubing.
 6. A method of installing a tubing encapsulated cable comprising: inserting a cable into an end of a coil tubing, wherein the coil tubing is spooled, pumping fluid into the end of the coil tubing, moving a first end of the cable through the coil tubing, connecting a second end of the cable to a tubing encapsulated cable, applying tension to the cable, and pulling and vibrating the tubing encapsulated cable through the coil tubing.
 7. The method of claim 6 wherein, the first end of the coil tubing has a flow tee.
 8. The method of claim 6 further comprising, connecting the first end of the cable to a winch after the first end of the cable moves through the coil tubing.
 9. The method of claim 6 further comprising, connecting the first end of the cable to a plug prior to moving the first end of the cable through the coil tubing.
 10. The method of claim 6 further comprising, pumping the coil tubing through the coil tubing while pulling and vibrating the tubing encapsulated cable. 